Table saw having a measurement and display system

ABSTRACT

A table saw having various embodiments of a measurement and display system. Several embodiments have at least one fence rail on which a removable fence is movably supported and comprise an elongated sensor strip that is located adjacent the fence rail and a sensing unit that is supported and positioned adjacent to the sensor strip and is capable of providing an electrical signal to a display unit that is indicative of the position of the sensor unit relative to the elongated sensor strip. A processing unit is operatively connected to the sensing unit and display unit to provide a digital readout of the position of the sensing unit. A switch is connected to the processing unit and is adapted to provide a zero or reference setting position.

This is a divisional of application Ser. No. 10/823, 270, filed Apr. 13,2004.

BACKGROUND OF THE INVENTION

Table saws of the type which have a circular cutting blade are wellknown and have been used by tradesmen and woodworkers for decades.Because they have a generally flat surface, large and small boards aswell as plywood sheets can be cut to the appropriate size by typicallysetting a fence at the appropriate position to perform a cut along adesired line which is done by pushing the board or sheet across thetabletop and through the blade. Typically, the fence is adjustable bysliding along an elongated rail anchored at opposite ends of the tablesaw top, with the fence having a clamping mechanism to lock the fenceonce it has been placed in the desired position. Most users, when theyknow the width of the desired board will use a tape measure or othermeasure to position the fence to obtain the desired width by measuringbetween the edge of the blade to the fence. After the fence is inposition, it is locked in place and users typically remeasure thedistance to make sure that they have the fence in the correct position.

While the manual measurement and setting of the position of the fence isthe manner in which the fence has been positioned by most users over theyears, in some instances it is highly desirable to have very accuratemeasurements which may be difficult depending upon the type of measuringdevice is being used. Most tape measures, for example, do not haveaccurate measurements beyond a 1/32 of an inch or less. Also, if thefence is moved during other types of cuts, it is not possible to resetthe fence at exactly the same position that was used for a prior cutwithout going through the complete exercise again. If the user does notremember the prior cut distance, then additional measurements of awork-piece may be necessary in order to obtain the distance which mustthen be used to correctly position the fence.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a first preferred embodiment of a table sawhaving a measurement and display system;

FIG. 2 is a front view of a second preferred embodiment of a table sawsimilar to the table saw shown in FIG. 1, but having a tabletopextension shown in an extended position;

FIG. 3 is a cross-section taken generally along the line 3-3 of FIG. 2;

FIG. 4 is a front view of a portion of the table saw shown in FIGS. 1and2;

FIG. 5 is a section taken generally along the line 5-5 of FIG. 4; and

FIG. 6 is a front view of a third preferred embodiment illustrating adisplay unit having additional functionality relative to the displayunit shown in FIG.4.

FIG. 7 is a perspective view of an idealized illustration of a thirdpreferred embodiment of a table saw having a measurement and displaysystem;

FIG. 8 is an end view of the embodiment shown in FIG. 7 and illustratinga mounting bracket in phantom;

FIG. 9 is an enlarged perspective of a portion of the embodiment shownin FIG. 7;

FIG. 10 is a perspective view of an idealized illustration of a fourthpreferred embodiment of a table saw having a measurement and displaysystem;

FIG. 11 is a perspective view of an idealized illustration of a fifthpreferred embodiment of a table saw having a measurement and displaysystem;

FIG. 12 is a perspective view of an idealized illustration of a sixthpreferred embodiment of a table saw having a measurement and displaysystem; and

FIG. 13 is a perspective view of an idealized illustration of a seventhpreferred embodiment of a table saw having a measurement and displaysystem.

SUMMARY OF THE INVENTION

A table saw having a measurement and display system has at least onefence rail on which a removable fence is movably supported. Severalembodiments have an elongated sensor strip located adjacent the fencerail and a sensing unit that is supported and positioned adjacent to thesensor strip and is capable of providing an electrical signal to adisplay unit that is indicative of the position of the sensor unitrelative to the elongated sensor strip. A processing unit is operativelyconnected to the sensing unit and display unit to provide a digitalreadout of the position of the sensing unit. A switch is connected tothe processing unit and is adapted to provide a zero or referencesetting position and this embodiment may include a second switch forchanging between English and metric units.

A second preferred embodiment includes a table extension which can bemoved to increase the effective size of the table saw top so that largerwork pieces can be supported during cutting. In this embodiment, thefence rail is connected to an extension rail so that the fence railmoves with the extension to thereby increase the range of the sensorstrip and sensing unit for providing larger measurements.

A third preferred embodiment includes a more sophisticated display andprocessor functionality, which, among other things, can display Englishunits in decimal or fractions as well as store and recall importantdistance measurement positions.

A fourth preferred embodiment includes a mounting mechanism that enablesa relatively short and inexpensive sensor strip to be selectivelypositioned to increase the range of measurement of a fence along thewidth of the table saw and to adjust the measurement as a result of theposition of the sensor strip.

A fifth preferred embodiment operates with a sensing rail that islocated on the front of the table saw, but has all other operativeelements mounted on the fence.

Sixth and seventh preferred embodiments operate with a string or tapeposition transducer device that interconnects a stationary location onthe table saw and the movable fence.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A first embodiment of a table saw of the present invention is shown inFIGS. 1, 2 and 3 and illustrates a table saw, indicated generally at 10,of the type which is configured to be supported by a table 12 or othersupport structure or frame having legs. It should be understood that thetable saw 10 could be of the type which has its own support stand andmay be more permanent rather than the one illustrated which is oftenreferred to as a portable saw. The saw 10 has a base 14 in which the sawmotor (not shown) is located with the motor driving a blade 16, theheight of which can be adjusted by conventional adjustment means (notshown) and which can also be angularly adjustable by an assembly thatincludes a wheel 18.

The saw 10 has a main tabletop 20, a tabletop extension 22 and anadjustable fence, indicated generally at 24, that has a handle 26 thatcan be raised and lowered to lock the fence in a desired lateralposition relative to the blade. The fence has a base portion 28 that isslidably adjustable along a fence rail 30 that extends substantially thefull width of the saw. While not illustrated, the fence preferably hasits opposite end configured to ride on another fence rail whichfacilitate its sliding lateral movement, i.e., left and right as shownin FIG. 1.

The table saw 10 illustrated in FIG. 1 is shown with the extension 22 inan unextended position whereas in FIG. 2, the extension 22 is extendedoutwardly to the right. This is achieved by a locking knob 32 beingloosened so that the fence rail 30, which is supported by an extensionrail 34 can be moved along the extension rail 34. It should beunderstood that the fence 24 in FIG. 2 has been moved relative to itsposition in FIG. 1 to more clearly illustrate the manner in which theextension 22 moves relative to the extension rail 34. The configurationwhich particularly illustrates the interoperability of the fence rail 30and the extension rail 34 is shown in FIG. 3, with the extension rail 34having a base portion 36 that is connected to the main top 20 by bolts38, screws, weldments or the like, with short transverse segment 40extending away from the base 36 and then outwardly to form flanges 42and transverse end segments 44. The configuration provides a narrowspace 46 between the top 20 and the extension rail 34 so that the fencerail 30 can easily slide relative to the extension rail 34 but be heldcaptive so that any appreciable vertical and horizontal movement betweenthe two components is prevented. An end cap 48 made of plastic orplastic-like material is preferably provided at opposite ends of thefence rail 30 and is preferably a resilient material that can besnap-fit into the interior of therail30.

As best shown in FIGS. 1, 2 and 3, a display rail 50 is positioned belowthe fence rail 30 and is attached thereto by two brackets 52 which arelocated at opposite ends of the fence rail 30. The brackets 52 have afront upper flange 54 upon which a spacer 56 is positioned with theflange 54 and spacer being connected to the fence rail 30 by a bolt 58and nut 60, screws, weldment or other equivalent attachment means. Theopposite ends of the display rail 50 are attached to the bracket 52 bysuitable screws, adhesive, bolts or the like (not shown). The displayrail has a base portion 62 as well as transverse end portions 64 andreturn flanges 66 which define a recess in which a display unit,indicated generally at 70, can be inserted and be held captive so thatvertical and horizontal movement is prevented but which will permitsliding lateral movement, i.e., left or right as shown in FIGS. 1 and 2.

On the backside of the bracket 52 a sensor strip 72 is attached byscrews, bolts, adhesive or the like. A sensor strip 74 is attached tothe sensor strip 72, preferably using an adhesive material. While thecross section of the sensor strip 74 is shown in FIG. 3 and is thereforeillustrated to be located at the left end of the sensor strip 72. Inactuality, the length of the sensor strip 74 is preferably within therange of about 15 to about 25 inches and preferably about 20 inches withthe left end of the sensor strip being approximately coextensive withthe blade and extending to the right end thereof as shown in FIG. 1. Inthis regard, the drawing is technically in error, but does generallyshow the relative size and configuration of the strip relative to thesensor strip. It should also be understood that when the extension 22 ismoved to the right as shown in FIG. 2, the left end of the sensor strip74 will move to the right of the blade 16.

It should be understood that another preferred embodiment of the tablesaw may not include the extension 22 and therefore would not need tohave the extension rail 34, in which case the fence rail 30 would beattached directly to the table top 20 or other structure associated withthe frame because the fence rail 30 would not move laterally.

As shown in FIG. 4, the display unit 70 has an electronic display 76that is mounted to a display block 78 that is preferably a unitary pieceof aluminum or other metal that has an angled front face 80 with asuitable recess (not shown) in which the display 76 can be inserted,with the ends extending further outwardly so as to provide someprotection against damage during use. The right end of the block 78 hasa vertically oriented slot 82 that has a width that is closely matchedto the outside diameter of a pin 84 that is attached to the fence base28. The pin 84 therefore causes the display unit 70 to move with thefence as it is laterally adjusted during use. Since the pin 84 merelyrides in the slot 82 of the block 78, the fence 24 can be lifted withoutdifficulty from the table saw. However, when it is lowered into place sothat the fence base 28 rides on the fence rail 30, the pin 84 is closelyfits in the slot 82. The display 76 has a ribbon connector 86 thatextends to a sensor 88 that is secured to the display block 78 by a bolt90, although adhesive or other attachment means may be used. The sensor88 is configured relative to the sensor strip 72 so that the necessarytolerances between the two are maintained as the sensor 88 is movedalong the sensor strip.

A sensor 88 is secured to the display block 78 by bolts 90 and thesensor strip 72 has copper pads along its length that are positioned toprovide a changing capacitance that is sensed by the sensor element 58and which can thereby provide accurate measurement of incrementalpositions along the length of the rail. In this regard, it is preferredthat the sensor strip 72 and sensor 88 be similar to those that arepresently used in commercially available digital calipers. Other linearsensor technologies based on inductance, magnetostrictive effects orresistive elements can also be used.

The display 76 has a front panel with a pushbutton switch 96 which is azero set switch and a switch 98 which toggles between English and metricsystems in the display window 100. The display window is preferably aLCD display which has four integers 102 and a decimal 106 as well as afield 108 indicating inches or millimeters.

During operation, when the fence 24 is positioned abutting the blade 16,for example, an operator can depress the zero set pushbutton 96 whichwill result in the display window readout indicating a zero position.That having been done, if the user wants to position the fence so that asix inch wide cut of a work piece is desired, the fence 24 can be movedto the right until the display indicates that the fence has been moved6.00 inches (or the appropriate millimeter conversion) at which time theuser can lock the fence 24 in position by moving the lock handle 26downwardly in the illustrated embodiment.

If during the locking of the fence, the fence moves either left or rightas shown in FIG. 4, the display 76 will so indicate, which enables theuser to unlock the fence and correctly position it until the exactdistance of six inches is locked into position. If the sensingstrip/sensor has a 1/100 inch or 1/10 millimeter degree of accuracy, thefence can be positioned to that degree of accuracy.

Turning to another preferred embodiment of the present invention andreferring to FIG. 6, a display 110 is shown which has additionalfunctionality. More particularly, the display has a pushbutton 112 whichtoggles between English and metric units and has a six integer displaywith two decimal points and a slash indicator which enables Englishunits to be displayed in hundredths or in fractions and metric units tobe displayed in thousandths or ten thousandths of an inch. Additionally,the display includes a zero pushbutton 114 as well as a store pushbutton116 and a recall pushbutton 118 as well as an offset pushbutton 120. Thedisplay is also operable to set and utilize a DADO blade offset as wellas a fence offset in either 1/16 or 1/32 increments which enables a userto appropriately set the position.

Another embodiment of the present invention is shown in FIGS. 7-9 whichcomprises a table saw having a table top 20 that has an opening throughwhich a saw blade 16 is positioned. A fence indicated generally at 24′has a base 28′ that has a recess which cooperatively engages a fencerail 130 and is configured to slide along the fence rail 130 and beclamped to it. While the diagrammatic illustration of the fence 24 shownin FIGS. 7, 8 and 9 is greatly simplified, it should be understood thata clamping or locking mechanism is preferably provided as is known tothose of ordinary skill in the art.

The fence rail 130 is attached to the table 20 by suitable bolts or thelike that are located inside a pair of standoffs 131 which appropriatelyspace the fence rail from the front edge of the tabletop 20. A display70′ is mounted on a block extrusion 132 that is coupled to the base 28′of the fence 24′. The block extrusion 132 has an angled front portion134 to which the display 70′ is attached and the top of the frontportion 134 has a forwardly directed flange 136 that is substantiallyparallel to the base 28′ of the fence. A pin 138 mounted to the base 28′extends into a slot in the flange 136 with the width of the slot beingsubstantially equal to the outside diameter of the pin 138 so thatmovement of the fence along the sensing rail 130 will also move theblock extrusion 132.

The block extrusion 132 also has a middle portion 140 that extends inthe rearward direction and carries a T-shaped cross section 142 as wellas a rearward extension 144 that is vertically oriented and provides asurface to which a sensing unit 146 is mounted. A flexible ribbon cablesimilar to the ribbon connector 86 shown in FIG. 5 interconnects thesensing unit 146 to the display module 70′.

The sensing unit has an opening 148 through which a sensing rail 150 ispositioned, the sensing rail being mounted at opposite ends to anextension rail 152. The extension rail 152 has a pair of rearwardextensions 154 which have transverse extensions 156 that are directedtoward each other and encompass the T-shape portion 142 of the blockextrusion. The block extrusion 132 is supported by and can move relativeto the extension rail 152 enabling the sensing unit 146 to provide ameasurement of the position along the sensing rail 150 and provide adigital output of the position. Importantly, the length of the extensionrail 152 is slightly greater than the length of the sensing rail 150 anda pair of brackets at each end attach the extension rail 152 to thesensing rail 150. The extension rail is itself supported and heldcaptive in the fence rail 130 which has an inclined inside front portion160 that has a lower angled flange 162 and an upper flange 164 whichsurround the extension rail 152. The extension rail 152 is movablerelative to the fence rail 130 by a distance that is approximately equalto the length of the slot 166.

As is best shown in FIG. 7, the fence rail 130 has an elongated slot 166through which a threaded bolt 168 is located, with the bolt having aknob 170 that can be rotated to tighten or loosen the bolt 168 which isthreaded into an opening in the extension rail 152. When it is loosened,the extension rail may be moved so that the knob will be moved along thelength of the slot 166 which is approximately 12 inches in theillustrated embodiment. This means that the length of the sensing rail150 is approximately the same length, with the width of the tabletop 20being approximately two feet in total. However, it should be understoodthat a shorter or longer slot may be provided.

When the knob 170 is loosened, the extension rail 152 can be moved alongthe slot 166 from the position that is shown to the far left end asshown in FIG. 7. Indicia such as a green dot 176 near the left end and ared dot 178 on the right end are provided together with green and redswitches 176 and 178, respectively, which the operator can pressdepending upon which end the knob 170 is positioned. By so doing, theprocessing means in the display module 70′ can automatically compensatefor the changed position relative to the blade 16. In this way, a 12inch long sensing rail can be used to effectively measure across theentire width of the table. This is advantageous because the cost ofsensing systems and particularly sensing rails dramatically increaseswith increased lengths.

A fifth preferred embodiment is shown in a simplified diagrammaticfashion in FIGS. 10 and 11, and has a removable fence 24″ with a base28″ that is configured to be supported on a fence rail 190 that ispreferably an extrusion with a flat top and a front recess 192 which isconfigured to receive a sensing rail 194 that is attached to the rail bysuitable means such as an adhesive, mechanical clips, screws, or thelike. The fence rail 190 is attached to the saw table top 20 by two ormore bolts 196 which extend from the fence rail 190 to the top 20through standoffs 198 as shown in FIG. 11.

As is shown in FIG. 10, the sensing rail 194 extends substantiallyacross the entire front of the table saw. The fence 24″ has a mountingbracket 200 attached thereto for providing a support for a displaymodule 70″ that may have structure and functionality that is similar tothe structure of the display module 70 or 76. A sensor unit 202 ismounted to the bottom 28″ of the fence 24″ and is positioned adjacentthe sensor strip 194. An advantage of this embodiment is that allcomponents except the sensor strip 194 are mounted to the fence 24″, andno wires between the sensor unit 202 and the display module 70″ need tobe exposed and therefore susceptible to damage during use. The fence canbe easily removed from the table saw without the necessity ofdisengaging any parts, unplugging cables or other inconveniences.

A sixth preferred embodiment is shown in FIG. 12 and has a rotationalposition transducer unit 210 that is mounted to the table saw 212 andhas a flexible tape 214 extending from the unit that extends to and isconnected to a bracket 216 to which a display module 218 is attached.While a tape 214 is shown, it should be appreciated that a cable orstring type of unit is commercially available and may be used.Regardless, the tape 214 is held under tension by a spring mechanism inthe position transducer unit 210 and the unit generates an electricalsignal that is indicative of the amount of tape or string that is pulledout of the unit 210. The bracket 216 is supported by and slides along abottom portion 220 of an extrusion 222 that extends along the front ofthe saw 212. The extrusion has a recess 224 in which a fence 226 canslide with fence having a base portion 228 that has a downwardlyextending pin 230 that can fit within a hole in the bracket 216. Thisenables the fence 226 to be removably coupled to the bracket 216. Whilenot shown, the fence preferably has a locking mechanism to hold thefence in the desired position when that is determined. Power foroperating the unit 210 can be provided by an AC source through cords232, 234 and transformer 236. Alternatively, a battery may be used ifdesired.

The tape 214 can be attached to either the bracket 216 or the displayunit 218 as desired. As the fence and bracket 216 are moved along thefront of the table saw 212, the tape 214 is wound and unwound from theunit and an electrical signal is generated and is communicated to thedisplay unit 218. In this embodiment, the communication is preferablyaccomplished by an infrared transmitter in the unit 210 and an infraredreceiver in or adjacent to the display unit 218. Other types ofcommunication can be used as desired. Also in this embodiment, a zerobutton is used to calibrate the position of the fence at a zero positionrelative to the blade as has been previously described with regard toother embodiments, enabling the distance from the fence 226 to the bladeof the saw to be displayed as the fence 226 is moved away from the bladethe desired distance. An advantage of this embodiment is that theincremental cost for increased distances is significantly lower than formany other types of sensing strips or rails.

A seventh embodiment is shown in FIG. 13 and is similar to theembodiment of FIG. 12, except that a rotational position transducer unitis located within a display unit module 240 has a fence 242 mounted toit. While not shown, the fence 242 is preferably removable from themodule 240 and a locking mechanism is either associated with the fence242 or the module 240. A tape 244 extends from the module 240 and isattached to a bracket 246 or the like that is attached to the table saw.This embodiment has an extrusion 248 that is similar to the extrusion222 of FIG. 12 in that it has a lower portion 250 on which a bracket 252is slidably attached. The bracket 252 is attached to and carries thedisplay module 240. The operation of this embodiment is substantiallysimilar to the embodiment shown in FIG. 12, but has the advantage thatthe position transducer unit is directly connected to the display unitand no independent communication capability is required.

With regard to all of the embodiments described above, the sensing unitand sensor strip may have copper pads along its length that arepositioned to provide a changing capacitance that is sensed by thesensor unit and which can thereby provide accurate measurement ofincremental positions along the length of the rail. In this regard, itis preferred that the sensor strip and sensor element be similar tothose that are presently used in commercially available digitalcalipers. However, other linear sensor technologies based on inductance,magnetostrictive effects, resistive elements or optical encodedtechniques can also be used without departing from the spirit and scopeof the invention.

While various embodiments of the present invention have been shown anddescribed, it should be understood that other modifications,substitutions and alternatives are apparent to one of ordinary skill inthe art. Such modifications, substitutions and alternatives can be madewithout departing from the spirit and scope of the invention, whichshould be determined from the appended claims.

Various features of the invention are set forth in the following claims.

1. A linear measurement and display system for a table saw of the typewhich has a removable fence that is laterally adjustable relative to theblade of the saw along a fence rail located on the front of the tablesaw, said system comprising: a sensor strip positioned generallyparallel to the fence rail, said sensor strip configured to providedigital signals that are indicative of specific positions along thelength thereof; a sensing unit movable along said sensor strip andoperatively connected to the fence, said sensing unit generating signalsindicative of the specific lateral position of the fence; a switchoperatively connected to a processing unit for establishing a referenceposition when activated; a processing unit connected to said sensingunit for receiving said position indicating signals and for calculatingthe distance between said fence and said reference position and forgenerating display signals indicative of said calculated distance; and adisplay unit electrically connected to said processing unit configuredto receive said display signals and provide a digital display of saidcalculated distance.
 2. A system as defined in claim 1 wherein saidsensor strip is connected to the fence rail.
 3. system as defined inclaim 1 further comprising a member physically connecting said sensingunit, said display unit and said processing unit together, the fencehaving a pin for engaging a slot in said member, whereby the fence isphysically coupled to said sensing unit when the fence is attached tothe fence rail.
 4. A system as defined in claim 1 wherein saidprocessing unit is capable of generating display signals that cause saiddisplay unit to display said calculated distance in one of English ormetric units.
 5. A system as defined in claim 1 wherein said processingunit is housed with said sensing unit, said table saw further comprisinga battery for powering said processing unit and said sensing unit.
 6. Asystem as defined in claim 1 further comprising a display rail extendingparallel to said sensor strip, said display unit being slidable alongsaid display rail and being mechanically and electrically connected tosaid sensing unit and said processing unit.
 7. A system as defined inclaim 1 further comprising a table top extension that abuts said maintable top and at least one table extension rail, said table topextension being connected to the fence rail, the fence rail beingslidably attached to said table extension rail so that said table topextension can be separated from said main table top to increase theeffective area of the top of said table saw.
 8. A system as defined inclaim 6 wherein at least one ribbon connector electrically connects saidsensing unit with said display unit and said processing unit.
 9. Asystem as defined in claim 3 wherein said switch is mounted adjacentsaid display unit.
 10. A system as defined in claim 3 further comprisingan on/off switch for controlling power to said processing unit.
 11. Asystem as defined in claim 3 further comprising a switch for selectivelyalternating between English and metric units of length.